1. Technical Field
Exemplary embodiments of the present disclosure relate to swivel joints, and more specifically, to electrical conductivity grease fittings for establishing and maintaining electrical conductivity in a swivel joint and lubricating moving parts thereof.
2. The Relevant Technology
Loading or unloading arms are used to assist in the transfer of various materials, wet or dry, from a supply source to a container, tanker car or truck in which materials are transported or shipped, or a vehicle, such as an airplane. Often, loading arms can be quite heavy and can be of considerable length. Swivel joints generally include a mechanism, such as a bearing assembly, to make it easier to move the loading arm, and align it with the relatively small opening of a container. To maintain the proper functioning of the bearing assembly, swivel joints often include a grease fitting that allows for lubricant to be applied to the bearing assembly.
During the loading of various materials, static electricity may be generated. The voltage potential created causes the excited electrons to seek an area of lower voltage potential. Surrounding metal, such as the loading arm, the container, or both can provide a low resistance to electrons and thus, may attract the electrons. Such static electricity should be dissipated preferably by routing or directing it to the ground, to the loading rack, or both.
Swivel joints, however, do not necessarily dissipate static electricity. In some instances, they do not have a tight or constant metal-to-metal contact because they are configured to permit relative rotational movement of the components to position the loading arm, as desired. Grease, oil and other lubricants often fill the cavity between the adjacent components further inhibiting metal-to-metal contact. Effective breaks in the metal-to-metal contact for periods of time may electrically isolate adjacent components, thereby hindering the dissipation of static electricity.
In some cases, the material being routed through a loading arm may offer a path of less electrical resistance that the electrical conductivity offered by the adjacent metal components of the swivel joint (e.g., the tail and body sections). Such a situation could result in an undesirable consequence, and/or serious injury, especially if the material being routed through the loading arm is volatile, such as gasoline, chemicals, and the like.